Door security system

ABSTRACT

An exit door security system which employs an electromagnet and armature to lock an exit door comprises an electromagnetic housing and a frame assembly. The housing is pivotally mounted to the frame assembly. An attempt to exit the door causes the housing to pivot to thereby actuate a switch. The lock is automatically released after a pre-established time delay. An alarm at the door may also be actuated by the switch. The electronic circuitry is configured to allow for immediate authorized egress and to implement an immediate safety release of the lock. The lock may be operated in either a normally locked or normally unlocked mode.

BACKGROUND OF THE INVENTION

This invention relates generally to electromagnetic locks which areemployed in connection with doors for controlling egress and/or accessthrough the door. More particularly, the present invention relates toelectromagnetic lock systems which are adapted to provide for delayedegress through an exit door and/or a security alarm for monitoringegress.

Electromagnetic locks have been employed for a number of exitdoor/emergency door applications so as to provide an effective andreliable means for locking the door while also permitting egress throughthe door in emergency situations. A number of electromagnetic locksystems have incorporated a time delay implemented by various devices.The time delay systems effectively delay unlocking of theelectromagnetic lock for a pre-established time interval, such as 15 or30 seconds, to enhance security and control egress from a securedenclosure. A number of electromagnetic lock systems have alsoincorporated various devices for activating an alarm when an attempt ismade to egress through the associated exit or emergency door. Inaddition, a number of electromagnetic lock systems incorporate devicesfor releasing time electromagnetic lock in case of fire or otheremergency conditions.

Emanual L. Logan, Jr. et al, U.S. Pat. No. 4,720,128 discloses anelectromagnetic emergency exit door lock implementing a time delay foregress through a doorway. A switch is mounted adjacent to theelectromagnet and the switch is operated by a switch operator mounted onthe door. The switch provides a signal which indicates that an attemptis being made to open the door. The signal is used to sound an alarm orstart a time delay release of the electromagnetic lock. The switchcomprises a plunger, a magnet and a hall cell which are located within acompartment disposed beside the electromagnetic. When the door is closedand locked, a striker on the door engages the plunger of the switch.When a person in the enclosure presses either a panic bar or the insidesurface of the door so as to force the door to move slightly, theplunger moves to displace a magnet from the hall cell and generate asignal indicating someone is attempting to leave the enclosure.

Additional electromagnetic lock systems to which the invention relatesare set forth by patentee and U.S. Pat. Nos. in the Table below.

    ______________________________________                                        Patentee   U.S. Pat. No.                                                      ______________________________________                                        Frolov     4,957,316                                                          McFadden   4,487,439                                                          Logan      4,324,425                                                          Logan      4,257,631                                                          ______________________________________                                    

SUMMARY OF THE INVENTION

Briefly stated, the invention in a preferred form is an electromagneticlock in which the electromagnetic lock assembly is pivotably mounted toa frame or bracket assembly secured to the door frame. The armature ismounted to the door by means of a mounting arrangement which allowslimited pivotal movement of the armature. A switch is mounted to theelectromagnetic lock assembly so as to be actuated by pivotal or rockingmotion of the electromagnetic lock assembly upon attempting to open thedoor. The switch generates a signal which may be employed in connectionwith an instant or a time delay release for the electromagnetic lockand/or an alarm to alert that an attempt is being made to egress throughthe door and/or for other functions.

The pivotal mounting is provided by a pair of coaxial pivot pins havinga pivot axis which is substantially coplanar with the attraction surfaceof the electromagnet. The pivot axis is spaced from the center ofgravity of the housing. The frame assembly is mounted to the door frameso that the pivot axis is substantially horizontal and the housing ispivotal about the axis in a generally upward and downward direction. Theframe has a bottom plate which engages the bottom of the housing torestrict the downward pivotal movement of the housing. In addition,adjustable stop pins are mounted to the housing and engageable againstbase plate of the frame to restrict upper pivotal movement of thehousing.

Delay circuitry is mounted in the housing and is responsive to thesignal from the switch for deactivating the electromagnet after apre-established time interval. An audio alarm is also sounded at thehousing. A keyway is disposed in the housing and rotatable to a firstposition for terminating activation of the alarm. The keyway may berotatable to a second position for deactivating the electromagnet toallow for egress through the door. In the event of an emergency, thecircuitry also includes an override for automatically terminating powerto the electromagnet.

In one embodiment of the invention, a discriminator is provided fordiscriminating between door movement resulting from an internal forceapplied on one side of the door and an external force applied on theother side of the door. The discriminator generates a signal which isprocessed for selectively deactivating the electromagnet. Thediscriminator may comprise a passive infrared sensor. An auxiliaryswitch which is actuatable in response to an attempt to open the door isprocessed in series with the first signal from the rocking switch. Alegal entry override is also selectively activatable to simultaneouslydeactivate the electromagnet. A key pad or a card reader may be employedas an input terminal for the legal entry override.

In other embodiments of the invention, the circuitry is constructed toprovide for either a normal activated magnetic bonding mode of theelectromagnet or a normal unactivated bonding mode of the electromagnet.A sensor which may sense either a magnetic element, an electromagneticelement or a selected radio frequency is employed in the vicinity of thehousing for transforming the electromagnet to the activated bondingmode.

During the time delay interval, an LED mounted at the housing is pulsedby an oscillator, and a recorded message is transmitted from the housingto signal that the lock is subject to a time delay before release. TheLED is transformed to a steady state after the termination of the timedelay. In addition, an audio alarm may be pulsed during the time delayinterval.

An object of the invention is to provide a new and improved doorsecurity system which employs an electromagnetic lock incorporating anefficient means for releasing the lock for egress.

Another object of the invention is to provide a new and improved doorsecurity system which is easy to install and operates in a highlyreliable manner to secure and release exit doors.

A further object of the invention is to provide a new and improved doorsecurity system which employs an efficient and reliable means forimplementing a time delay to release of the electromagnetic lock and/oran alarm indicating that an egress is being attempted.

Other objects and advantages of the invention will become apparent fromthe drawings and the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the door security system in accordancewith the invention illustrated in conjunction with a door frame and anexit door and a latch mechanism therefor;

FIG. 2 is a side sectional view of the door security system of FIG. 1,partly broken away, illustrated in conjunction with a door frame and anexit door for the normal locked state;

FIG. 3 is a side sectional view of the door security system of FIG. 1,partly broken away, illustrated in conjunction with a door frame and anexit door for a position wherein an attempt is made to exit the exitdoor;

FIG. 4 is a rear view of the electromagnetic assembly of the securitysystem of FIG. 1, partly in schematic, with the back panel portion beingremoved;

FIG. 5 is a side view of the electromagnetic assembly of FIG. 4. partlybroken away and partly in section;

FIG. 6 is a side exploded view, partly broken away and partly insection, of the electromagnetic assembly of FIG. 4;

FIG. 7 is a front elevational view, partly broken away and partly insection, of the electromagnetic assembly of FIG. 4;

FIGS. 8A and 8B are a simplified schematic block diagram of the doorsecurity system of FIG. 1.

FIG. 9 is a simplified schematic block diagram of an alternate portionof the diagram of FIG. 8B; and

FIG. 10 is a simplified schematic block diagram illustrative of numerousother applications of the door security system of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the drawings wherein like numerals represent likeparts throughout the figures, a door security system in accordance withthe present invention is generally designated by the numeral 10. In thepreferred application, security system 10 is positioned in connectionwith an exit door 12 and a door frame 14 for controlling egress throughthe exit door and for selectively electromagnetically locking the exitdoor to prevent delay or control entry from the exit side of the door(left side in FIGS. 2 and 3) The door security system 10 has a widerange of applications and features and is not limited to application inconnection with an exit door.

The security system 10 is mounted at the top portion of the door and theupper underside of the door frame. The security system 10 communicateswith the power input and other system components via wires of a cable 16which extend in the door frame as will be detailed below. The doorsecurity system is employed in connection with a panic bar or push bar18 which releases a door latch 19 or with any other conventionallatching mechanism of the door. Alternately, the door security systemmay be employed without any latching device.

The door security system 10 comprises an electromagnet assembly 20 whichpreferably mounts at an upper underside portion of the door frame 14 andan armature assembly 30 which preferably mounts to the door 12. Theelectromagnet assembly 20 generates a magnetic field which bonds withthe armature assembly 30 to lock the door with the door frame as will bedetailed below. The electromagnet assembly comprises a bracket frame 22which receives and pivotally mounts a rectangular housing 24. Thehousing 24 mounts the electromagnet 26 and various other controls andcomponents as will be detailed below.

The bracket frame 22 comprises a base plate 40 having openings whichreceive fasteners 44 for securing the base plate to the underside of theupper door frame. The base plate 40 also includes an opening 46 for theelectrical cable 16 which leads from the security system to the externalpower source 13 and various associated remote components. A pair ofsubstantially identical, trapezoidal end plates 50 extend at opposingends of the base plate and receive screws 51 for mounting bottom panel52. The bottom panel 52 extends in general parallel relationship to thebase plate but has a transverse width which is less than thecorresponding width of the base plate.

The housing 24 has a substantially rectangular configuration which isdimensioned for limited pivotal movement within the bracket frame 22.The housing 24 mounts the generally E-shaped electromagnet 26. Theelectromagnet defines a generally frontally disposed planar attractingsurface 60, as best illustrated in FIG. 7. The housing has a pair oflaterally spaced end panels 58 having aligned bores which receivebushings 62. The end panels are adjacent the end plates 50 of thebracket frame. A pair of coaxial pivot pins 64 extend from the endplates and are received in the bushings so as to pivotally mount thehousing to the bracket frame assembly. The coaxial pivot pins aredisposed so that the pivot axis A of the pivot pins 64 is co-planar withthe attracting surface 60 and is located below the center of gravity G,as illustrated in FIGS. 6 and 7.

The housing 24 is dimensioned and oriented with respect to the bracketframe 22 to permit limited pivotal or rocking displacement of thehousing from the downward position illustrated in FIG. 2 to the upwardposition illustrated in FIG. 3. The downward position is defined by theinterference of the bottom panel 66 of the housing with the bottom panel52 of the bracket frame. A pair of laterally spaced stop pins 48 in theform of headed screws are threaded into the top of the housing andextend upwardly so as to project a small distance above the housing. Thedistance of projection above the housing top is adjustable. The upperpivotal position of the housing is defined by engagement of the stoppins 48 against the base plate 40.

A switch 70, such as a Burgess F4T7YC switch is mounted in the housing.The switch 70 includes an actuating arm 72 which projects through anopening 74 formed in the top panel of the housing. The actuating arm 72and the switch 70 are configured and positioned so that in the downwardpivotal position of FIG. 2, the arm does not contact the base plate 40or only lightly contacts the base plate, and in the upper pivotalposition of FIG. 3, the arm 72 sufficiently engages the base plate toactuate the switch 70.

The armature assembly 30, which may be similar to the armature assemblydisclosed in U.S. Pat. No. 4,957,316, comprises an armature plate 32 anda back plate 33. A fastener 34 has a head received in a recess of theplate 32 and an aperture of plate 33. The shank of the fastener isanchored by a nut which is received in a sleeve of the door. A spacercollar 35 is interposed between the door and the head of the fastener.The fastener 34 is configured so that it cannot be overtightened andprovides for limited pivotal movement of the armature plate 32 about thefastener, as best illustrated in FIGS. 2 and 3.

A rear cover 80 is secured to the housing body by two screws 82. Thecover 80 may be easily removed to provide access to a control module 84which is disposed rearwardly of the electromagnet 26. The control moduleincludes circuitry which connects with the switch 70 and includes anexteriorly visible indicator light 86 and a horn, siren or audio speaker88. In one embodiment, a time delay circuit is also incorporated intothe control module. The light 86 is a bi-color LED. When the LED isgreen, the electromagnet 26 is de-energized and the door is unlocked.The LED 86 pulses red flashes upon sending a delay request and continuespulsing throughout the delay time interval. A switch 92 which may beactuated by a key 94 inserted through the bottom panel of the frame andhousing also is electrically connected with the control module 84. Ayellow LED 158, which is visible only when the cover 80 is removed, isenergized when the power is on and switch 70 is in an actuated state.The positions of the switch 70, key switch 92 and other componentsillustrated in FIG. 4 may be reversed in relation to the ends of thehousing.

The door is latched to the door frame by latch 19 which is responsive tothe panic bar 18. A mortise lock (not illustrated) or any other devicewhich employs a mechanical latch may also be employed with the securitysystem 10. For some applications, the security system may be employed inconjunction with a door having no latch. Power from the power sourceenergizes the electromagnet 26 to magnetically bond with the armature tomaintain the door in a locked state. In case of smoke, fire or otheremergency, an alarm 98 overrides all other inputs and interrupts powerto the electromagnet to release the electromagnetic bonding and tothereby instantaneously unlock the door. Egress (right to left in FIGS.2, 3 and 10) through the door is permitted by releasing the latch 19 ina conventional fashion.

Under normal operating conditions wherein the door is locked and no exitis attempted, the pivotal orientation and locked state of the system isillustrated in FIG. 2. The armature is magnetically bonded t theelectromagnet to lock the door. The door is latched by the mechanicallatch 19 and cannot be opened without unlatching. The housing 24 ispivoted downward under the force of gravity due to the eccentricrelationship between the center of gravity of the housing and the pivotaxis A until the bottom of the housing engages the bottom plate 52 ofthe bracket frame. The floatable armature plate 32 follows theelectromagnet and maintains the engaged bonding relationship with theattracting surface due to the limited pivotal mount of the armature tothe door. In the FIG. 2 locked position, the actuating arm 72 is free,i.e., does not engage the base plate 40, and the switch 70 is notactuated.

With reference to FIG. 3, when an attempt is made to exit through thedoor, the push bar 18 is actuated to release the latch 19 and push openthe door. The force applied to the door is transferred through thearmature to the electromagnet. The resultant rotating moment around thepivot axis A tilts the housing in an upward pivotal position until thestop pins 48 at the upper rear edge of the housing engage the base plate40. At this position, further pivotal movement of the housing relativeto the frame assembly terminates, and the door for a time remains lockeddue to the magnetic force between the electromagnet 26 and the armatureplate 32. The limiting position defined by the stop pins 48 may beadjustable.

In the upward pivotal position, the actuating arm 72 of the switch isnow engaged against the base plate to thereby actuate the switch 70. Atime delay in the control module circuitry is commenced by actuation ofthe switch 70. The audio alarm 88 is simultaneously actuated. After apre-established time interval, which is typically 15 or 30 seconds,power to the electromagnet 26 will be interrupted to thereby unlock thedoor. The audio alarm will continue until it is manually reset by thekey switch 92. Regardless of the implementation of the delay interval,in the event of an emergency condition, such as smoke, fire or otheremergencies which may be detected at a remote station, power to theelectromagnet is interrupted thereby providing a delay-free egressthrough the door. The security system may also allow for instantdelay-free egress in some embodiments.

The pivoting or rocking electromagnetic housing which results inactuation of switch 70 generates a signal which is responsive to only aone-way-door movement to an open position (in the direction of the FIG.3 arrow). Door movement in the counter or closing direction or theabsence of door movement in the normal latched state will automaticallyresult in the switch assuming the unactuated state. The unactuated stateresults from the downward pivotal position of the housing under theforce of gravity.

The exit door security system 10 preferably includes a multi-functionand multi-option capability as illustrated by the schematic blockdiagram in FIGS. 8A and 8B. The power supply 15 which may have a plug-inor box mounted configuration, includes a transient suppression circuit110, a bridge rectifier 112 and a filler 114. The filtered power ispassed across fire alarm relay switch 116 to the magnetic power controlcircuit 118. The power output from control circuit 118 is applied to theelectromagnet 26 via a voltage selection switch 120 and a voltagesuppression circuit 122. The voltage selection switch 120 is set at theinstallation site to select the input power voltage, for example, 12 or24 volts. The filtered input voltage is also passed through a voltageregulator 124 and the regulated voltage is applied to all of thecircuits of the security system.

The fire alarm 98 communicates via an optical isolator 126 and aconfiguration switch 128 with a fire alarm relay 130 which governs theposition of the fire alarm switch 116. The switch, 128 is manually setin accordance with whether the associated fire alarm is configured tohave normally open or normally closed contacts. An Aromat PQ2E9V relayis suitable for fire alarm relay 130. Upon activation of the fire alarm98, power is essentially removed at the switch 116 to terminate thepower to the magnet 26 and thereby unlock the exit door.

A door status switch 132 of conventional form may be employed togenerate a signal for remote monitoring which indicates whether the dooris opened or closed. The switch may assume the form of a small magnetwhich is concealed in an aluminum member attached to the end of thearmature plate 32. The sealed magnet actuates a magnetic reed switchmounted on the inside of the housing 24.

A magnetic bond sensor 134 which senses whether there is sufficientmagnetic holding force to ensure adequate locking of the exit door mayalso be employed. The magnetic bond sensor 134 is responsive to low linevoltage, and/or foreign material in the magnetic gap between theelectromagnet and the armature, and/or dirty or damaged surfaces of theelectromagnet and/or the armature. The magnetic bond sensor signal isalso generated to provide for remote monitoring.

A legal release input signal, which may be implemented by a selectedposition of key switch 92, allows for a door to be unlocked withoutdelay. The legal release input immediately interrupts power to theelectromagnet which remains unenergized as the contacts are closed andthe legal release input signals are present. No alarm or audio signal isgenerated while the legal release input is present. The signal isapplied via an optical isolator 136 to a lock status latch 144. Latch144 generates an input to the magnet power control circuit 118 toinstantly terminate power to the magnet 26. The legal release signal isalso applied to a legal release latch 138 which generates an output tothe relock delay timer 140 for initiating a relock sequence. The relocktimer 140 is adjustable over a period of 0 to 30 seconds for delayingthe energization of the electromagnet. When the legal release inputsignal terminates, the electromagnet is re-energized upon expiration ofthe delay period imposed by relock timer 140. The signal from the delaytimer 140 is applied to a relock monostable circuit 142 whichcommunicates with the lock status latch 144. The output from latch 144is applied to the power control circuit 118 to maintain either anenergized locked status for the electromagnet or an unenergized releasedstatus. In addition, the output signal from the monostable circuit 142is applied to the legal control logic circuit 146, which functions tocontrol legal egress through the exit door by controlling the relockingsequence. The legal release may be generated from local devices such asa local key switch 92 or a remote terminal 150 such as a remote pushbutton, a key pad, a card reader or an access control terminal at theentrance side of the exit door.

An auxiliary input signal indicative of an unauthorized exit request isapplied via an optical isolator 152 to a detect/auxiliary logic circuit154. The other input to logic circuit 154 are signals from the sensorswitch 70 and signals from auxiliary configuration switches 156 and 157.Switch 70 essentially provides an unauthorized exit detection signal.The auxiliary input may originate from various sources such as from aswitch in the panic bar or another motion or presence actuated switchand may be employed as a redundant sensor signal in conjunction withswitch 70. Bi-stable switches 156 and 157 are mounted on the circuitboard and are each settable by removing cover 80 and setting each switchto one of two states A and B. Logic circuit 154 employs the input fromthe auxiliary input and the switches 156, 157 and 70 to perform thelogic set forth in Table I below:

                  TABLE I                                                         ______________________________________                                        Switch 156 Switch 157    Auxiliary Function                                   ______________________________________                                        A          B             Internal Only                                        B          A             External Only                                        A          A             External Parallel                                    B          A             External Series                                      ______________________________________                                    

In the internal only logic mode, only the switch 70 is used as thesensory input to indicate a request to exit. In the external only mode,the switch 70 is ignored as a sensory input, and the auxiliary inputinitiates the delay egress request as will be further described below.In the external parallel mode, either the sensory input from the switch70 or the auxiliary input will trigger a delay exit request andtherefore a redundant sensory input is provided. In the external serieslogic mode, both the internal switch 70 and an external contact closuregenerating the auxiliary input signal are required in order to initiatethe exit delay implementation for the system. The external series logicmode has.application in connection with a passive infrared sensor todistinguish between an opening force applied to the exit door from theinside as opposed to the outside of the exit door. A yellow indicatorLED 158 may be employed to indicate the lock status dictated by thelogic circuit 154.

The output from the logic circuit 154 is applied to a nuisance delaytimer 160. Timer 160 includes an adjustment for selecting a nuisancetime interval, e.g., 0 to 3 seconds, so that a false, inadvertent oraccidental sensed egress request such as, for example, door movement dueto stack pressure, does not initiate the delay egress sequence. Thenuisance adjustment may be implemented by a small screwdriver. Theoutput signal from the nuisance delay timer 160 is applied to the delayegress request latch 162 which starts the delay egress timer 164. Thedelay egress timer 164 is adjustable by 15 or 30 second selector switch166 which implements either a 15 or 30 second time delay (afterexpiration of the nuisance timer 160 delay, if any) for release of theelectromagnet. At the end of the delay interval, an output signal fromtimer 164 is applied to the lock status latch 144 to release theelectromagnet.

The output signal from the delay egress request latch 162 is alsoapplied to an alarm latch 170. The alarm latch 170 generates an alarmsignal which is transmitted to a remote location, such as a centralconsole or security station within the building. The output from thedelay timer 164 and the output from alarm latch 170 is applied to aspeech synthesizer 172. The speech synthesizer 172 generates an outputwhich is passed through an audio amplifier 174 to speaker 88. The audiotransmission speaker 88 may transmit a recorded message such as "AFTER A30 SECOND DELAY, THE EXIT DOOR WILL UNLOCK" or other appropriatemessage. In addition, the output from the alarm latch is applied to theindicator light 86. In a preferred form, the indicator changes from ared light to a green light upon release of the electromagnetic lock.

An alternative configuration for an alarm system which may replacesub-circuit 180 is illustrated in FIG. 9. The signal from the egressdelay timer 164 is applied to an oscillator 182. The oscillatory signalfrom the oscillator is then applied to a driver circuit 184 fortransmission to the horn 88 to generate an oscillatory audio alarm. Theoutput from the oscillator 182 is then applied to the LED 86 to drivethe LED at measured intervals, such as 1/2 to 1 second intervals. Theindividual requesting egress may essentially mentally count along withthe generated LED pulses to thus provide assurance that the lock releasecycle is in the process of implementation. The LED 86 and the alarm athorn 88 are transformed to steady states upon expiration of the egressdelay interval.

A reset input signal is applied via an optical isolator 178 to therelock monostable 142. The reset input signal functions to reset thesystem, e.g., to re-energize the electromagnet 26 and terminate thealarm. Although a remote reset is technically feasible, due to safetyregulations it is desirable for most applications that the reset beimplemented by the key switch 92. Alternatively, a separate local keyswitch (not illustrated) may be employed as a reset switch if the keyswitch 92 is located at a height beyond normal reach or a mortise-typelock is desired.

In preferred form, key switch 92 is a three position key switch whichselects normal operation, reset and legal egress modes. At the centerkey switch position, a normal operation is maintained. At a clockwisereset key switch position, which is momentarily held against spring biaswhich returns the key switch to the center position upon release, thereset input initiates locking of the door after a power up or followingan egress. The reset position will function only when the door isunlocked and will not terminate the egress delay unless the door isinitially unlocked. The clockwise reset position terminates the audioalarm and prepares the security lock system for the next delay request.A counter-clockwise legal key switch position, which is a stableposition, allows for instantaneous legal egress wherein the door isimmediately unlocked. No alarm is generated and the green LED isenergized in the legal egress mode. When the key is returned to thecenter normal position, the delay relock sequence begins or the key canbe turned to the releasable reset position to immediately lock the door.

A power on reset switch 168 is employed for selectively implementing alock status mode where either the electromagnet 26 is normally on, i.e.,energized or is normally off. As will be described below, a number ofapplications for the security system require that the lock status benormally off.

With reference to FIG. 10, the security system 10 provided by thedescribed electromagnetic lock circuitry is adaptable for implementationin connection with a wide variety of exit door configurations whichaccommodate selected safety, legal egress and security features. Thedescribed switches and logic circuits provide multi-option capabilitywhich is integrated with the conventional mechanical and latchinghardware. A single master unit of the security system is readilysuitably adjusted for the requirements of a given application. Forexample, the door may have an exterior key lock which provides for legalor authorized access through the exit door. A key pad, card reader orother electronic entry device 150 may be positioned at the exterior ofthe exit door to provide legal or authorized access to the enclosure. Inaddition, a sensor 192 which may take the form of a passive infraredpresence device, a device which senses the presence of a magneticmaterial, a device which senses the presence of an electromagneticmaterial or field, a device which is responsive to a selected radiofrequency, or other sensory device may be mounted at the interior of theenclosure in the vicinity of the electromagnet assembly 20. The key pad150, key lock 190 and sensor 192 are naturally optional features whichif employed can provide a wide variety of security arrangements. Inaddition, it should be noted that the power on reset switch 168 may beset to either a normally on or normally off power mode for theelectromagnet when power is initially applied to the lock. In additionto the foregoing, the door itself may include locking/latching hardware194 which allows for the door to be selectively locked or unlocked withrespect to permitting access through the door from the exterior.

The sensor 192 may take the form of a passive infrared sensor whichsenses the presence of an individual at the door. The PIR sensorprovides either a redundant switch for actuating the time delay for theelectromagnetic lock or a means for discriminating between a doormovement (actuating switch 70) which is produced from inside of theenclosure as opposed to the outside. Alternatively, the sensor 192 maytake the form of a switch which is activated by the presence of amagnetic or electromagnetic object in the vicinity of the switch, suchas, for example, may be present in conventional shoplifting typesecurity installations. The sensor 192 may also be responsive to aselected radio frequency, such as, for example, may be generated by abracelet or other device which is worn by patients at a convalescenthome or other facility where it is desired to control egress through theexit door for a selected subset of the population. The sensor 192normally interrupts power to the lock until the sensor senses anindividual at the door or other activating event in which case the dooris locked.

In the latter application, the power on reset switch 168 may be set to anormally off position so that free access is normally provided throughthe exit door. However, when the sensor activates by sensing a selectedobject (individual) in the vicinity of the exit door, theelectromagnetic lock system is transformed to a normally locked state.Any subsequent attempt to open the exit door and thereby triggermovement of the door will initiate the implementation of the time delayperiod until the door is unlocked to provide a delayed egress throughthe exit door. It should be noted that instant legal egress may beprovided by the key switch 92 or other suitable input in addition to thenormal implementation of the time delay interval. In addition, a safetyoverride to immediately release the electromagnetic lock may be providedfor all of the various alternative configurations by means of the signalfrom the fire alarm 98 as previously described.

Even when one gains legal access such as by terminal 150 or lock 190, atime delay may be implemented via switch 70 to delay unlocking of thedoor. Likewise, the mechanical door latch 194 may be set to prevent orallow access through the exit door from the exterior.

A summary of various security system configurations which may beprovided in accordance with the invention is summarized in Table II. Itshould be noted that all of the configurations of Table II may alsoinclude a safety or fire alarm input override to provide instant safetyegress through the exit door.

                                      TABLE II                                    __________________________________________________________________________    AUXILIARY                                                                     OUTSIDE TABLE I    AUXILIARY                                                  MODULE  AUXILIARY  INSIDE  DOOR LATCH                                                                             NORMAL EM                                 PAD 150/                                                                              SWITCH     MODULE  STATUS   OPERATION                                                                              EXIT DOOR EXIT DOOR              LOCK 190                                                                              CONFIGURATION                                                                            SENSOR 192                                                                            LATCH 194                                                                              SWITCH 168                                                                             EGRESS    ACCESS                 __________________________________________________________________________    --      Internal   --      Unlatched OFF     Delay     NO                                                                  Instant Legal                    --      Internal   --      Latched   OFF     Delay     Delay                                                               Instant Legal                    Key Lock                                                                              Internal   --      Latched   OFF     Delay     Legal Delay                                                         Instant Legal                    Key Pad Internal   --      Latched   OFF     Delay     Instant Legal                                                       Instant Legal                                                                           Delay                  Key Pad Internal   --      Latched   OFF     Delay     Instant Legal          Key Lock                                     Instant Legal                    --      Series     IR      Latched   OFF     Delay     NO                                                                  Instant Legal                    Key Pad Series     IR      Latched   OFF     Delay     Instant Legal                                                       Instant Legal                    --      Internal   --      Unlatched OFF     Delay     Delay                                                               Instant Legal                    Key Pad Internal   --      Unlatched OFF     Delay     Instant Legal                                                       Instant Legal                                                                           Delay                  --      Series     IR      Unlatched OFF     Delay     NO                                                                  Instant Legal                    Key Pad Series     IR      Unlatched OFF     Delay     Instant Legal                                                       Instant Legal                    --      Internal   Sensor  Latched   ON      Free-if EM                                                                              NOt                                                                 activated                                                                     Delay-otherwise                  --      Internal   Sensor  Unlatched ON      Free-if EM                                                                              Free                                                                activated                                                                     Delay-otherwise                  Key Lock                                                                              Internal   Sensor  Latched   ON      Free-if EM                                                                              Legal                                                               activated                                                                     Delay-otherwise                  --      Internal   Sensor  Unlatched ON      Free-if EM                                                                              Free                                                                activated                                                                     Delay-otherwise                  --      Internal   Sensor  Latched   ON      Free-if EM                                                                              Delay                                                               activated                                                                     Delay-egress                                                                  Instant Legal                    Key Lock                                                                              Internal   Sensor  Latched   ON      Free-if sensor                                                                          Legal Delay                                                         activated                                                                     Delay-otherwise                                                               Instant Legal                    Key Pad Internal   Sensor  Latched   ON      Free-if sensor                                                                          Instant Legal                                                       activated Delay                                                               Delay-otherwise                                                               Instant Legal                    Key Lock                                                                              Internal   Sensor  Latched   ON      Free-if sensor                                                                          Instant Legal          Key Pad                                      activated                                                                     Delay-otherwise                                                               Instant Legal                    --      Internal   Sensor  Unlatched ON      Free-if sensor                                                                          Delay                                                               activated                                                                     Delay-otherwise                                                               Instant Legal                    Key Pad Internal   Sensor  Unlatched ON      Free-if sensor                                                                          Instant Legal                                                       activated Delay                                                               Delay-otherwise                                                               Instant Legal                    __________________________________________________________________________

It will be appreciated that the foregoing door security system 10provides a sophisticated electromagnetic lock for locking an exit doorwhile also providing a very efficient and reliable means for releasingthe lock either instantly or after a pre-established time delay and forsounding an alarm to ensure control over egress from the enclosure.Actuation of switch 70 is produced by door movement in the openingdirection only. The security system also provides for immediate legal orauthorized egress and implements a safety override for immediate egressin the event of an emergency. The signal from switch 70 in someapplications is not employed to release the lock (either instant ordelay) but may be employed for other functions relating to controllingegress and/or access through the door. For example, the signal fromswitch 70 may be employed as a signal indicative of an attempt to tamperwith a secured door.

While a preferred embodiment of the foregoing invention has been setforth for purposes of illustration, the foregoing description should benot be deemed a limitation of the invention herein. Accordingly, variousmodifications, adaptations and alternatives may occur to one skilled inthe art without departing from the spirit and the scope of the presentinvention.

What is claimed is:
 1. A security system for a door comprising:framemeans adapted for mounting to a door frame; housing means mounting anelectromagnet defining an attraction surface at one side of said housingmeans; pivot mounting means for pivotally mounting said housing means tosaid frame means; armature means adapted for mounting to a door andattractable by said electromagnet for magnetic bonding therewith; andswitch means mounted at said housing means and actuatable in response topivotal displacement of said housing means relative to said frame meansfor generating a first signal.
 2. The security system of claim 1 whereinsaid pivot mounting means comprise a pair of co-axial pivot pinsdefining a pivot axis substantially co-planar with the attractionsurface of said electromagnet.
 3. The security system of claim 2 whereinsaid pivot axis is spaced from the center of gravity of said housingmeans.
 4. The security system of claim 2 wherein when said frame meansis mounted to said door frame and said pivot axis is substantiallyhorizontal, said housing means is pivotal about said pivot axis in agenerally upward and downward direction.
 5. The security system of claim4 further comprising first restriction means for restricting downwardpivotal movement of said housing means relative to said frame means. 6.The security system of claim 5 wherein said frame means comprises abottom plate and said first restriction means comprises said bottomplate.
 7. The security system of claim 4 further comprising secondrestriction means for restricting upward pivotal movement of saidhousing means relative to said frame means.
 8. The security system ofclaim 7 wherein said frame means comprises a base plate and said secondrestriction means comprises adjustable stop pins mounted to said housingmeans and engageable against said base plate.
 9. The security system ofclaim 1 further comprising delay circuitry means mounted in said housingmeans, said delay circuitry means being responsive to said first signalfor deactivating said electromagnet after a pre-established timeinterval.
 10. The security system of claim 1 further comprising alarmmeans responsive to said first signal for activating a sensoryperceivable alarm.
 11. The security system of claim 10 wherein saidalarm means comprises a horn mounted at said housing means.
 12. Thesecurity system of claim 10 further comprising a keyway disposed in saidhousing means and a key receivable in said keyway and rotatable to afirst position for terminating activation of said alarm.
 13. Thesecurity system of claim 12 wherein said key is rotatable to a secondposition for deactivating said electromagnet.
 14. The security system ofclaim 1 further comprising power supply means for selectively supplyingelectrical power to said electromagnet and safety means forautomatically terminating power to said electromagnet in the event of anemergency.
 15. The security system of claim 1 further comprising releasecircuitry means mounted in said housing means and responsive to saidfirst signal for deactivating said electromagnet.
 16. The securitysystem of claim 15 wherein said switch means comprises an actuating armand said housing means is pivotal between first and second pivotalpositions, said actuating arm being unactuated in the first pivotalposition and actuated in the second pivotal position.
 17. A securitysystem for a door comprising:frame means comprising mounting means andlaterally spaced end support means; housing means mounting anelectromagnet defining an attraction surface at one side of said housingmeans; pivot mounting means pivotally mounting said housing means tosaid end support means, said housing means being received in anenclosure defined by said frame means and pivotal between first andsecond pivotal positions; armature means attractable by saidelectromagnet for magnetic bonding therewith; and switch means having anunactuated state at said first position and an actuated state at saidsecond position for generating a first signal.
 18. The security systemof claim 17 wherein said frame means comprises a base plate and saidswitch means is mounted at said housing means and comprises an actuatingarm engageable with said base plate at the second position.
 19. Thesecurity system of claim 17 wherein said electromagnet and armaturemeans are magnetically bondable at both the first and second positions.20. An exit door security system comprising:housing means mountingelectromagnet means for generating a magnetic field; armature meansadapted for mounting to a door and attractable by said electromagnetmeans for magnetic bonding therewith; switch means mounted at saidhousing means and actuatable in response to reactive movement of saidhousing means resulting from movement of said door for generating anegress request signal; discriminator means for discriminating betweendoor movement resulting from an internal force applied on one side ofsaid door and an external force applied on the other side of said doorand generating a discriminator signal indicative thereof; and circuitmeans responsive to said egress request signal and said discriminatorsignal for selectively deactivating said electromagnet means.
 21. Thesecurity system of claim 20 wherein said discriminator means furthercomprises a passive infrared sensor.
 22. The security system of claim 20wherein said discriminator means further comprises an auxiliary switchmeans actuatable in response to an attempt to open the door forgenerating an auxiliary signal, said request signal and said auxiliarysignal being processed in series.
 23. The security system of claim 20further comprising legal entry means selectively activatable tosubstantially simultaneously deactivate said electromagnet means. 24.The security system of claim 23 wherein said legal entry means comprisesa key switch mounted to said housing means and a corresponding key, saidlegal entry means being activatable in response to rotation of said keyin said key switch.
 25. The security system of claim 23 wherein saidlegal entry means further comprises a key pad.
 26. The security systemof claim 23 wherein said legal entry means further comprises a cardreader.
 27. An exit door security system comprising:housing meansmounting electromagnetic means activatable for generating a magneticfield; armature means adapted for mounting to a door and attractable bysaid electromagnetic means for magnetic bonding therewith; switch meansmounted at said housing means and actuatable in response to reactivemovement of said housing means resulting from movement of said door inan opening direction for generating a first signal; mode means forselectively implementing either a normal activated magnetic bonding modeof said electromagnet means or a normal unactivated bonding mode of saidelectromagnet means; and delay circuit means responsive to said modemeans and said first signal for deactivating said electromagnet meansafter a pre-established delay interval.
 28. The security system of claim27 further comprising sensor means for detecting the presence of amagnetic element and transforming said mode means to an activatedbonding mode.
 29. The security system of claim 27 further comprising RFsensor means for detecting a selected radio frequency generated in thevicinity of said housing means and transforming said mode means to anactivated bonding mode.
 30. The security system of claim 27 furthercomprising sensor means for detecting the presence of an electromagneticelement and transforming said mode means to an activated bonding mode.31. The security system of claim 27 further comprising legal egressmeans selectively actuatable for immediately deactivating saidelectromagnet means.
 32. The security system of claim 27 furthercomprising safety means automatically actuatable in response to anemergency for immediately deactivating said electromagnet means.
 33. Adoor security system comprising:housing means mounting electromagnetmeans activatable for generating a magnetic field; armature meansadapted for mounting to a door and attractable by said electromagnetmeans for magnetic bonding therewith; switch means mounted at saidhousing means and actuatable in responsive to reactive movement of saidhousing means in response to movement of said door in an openingdirection for generating a first signal; light emitting means mounted atsaid housing means for emitting a visible light; and circuit meansresponsive to said first signal for deactivating said electromagneticmeans after a pre-established delay interval, said circuit meanscomprising oscillation means for pulsing said light emitting meansduring said delay interval.
 34. The security system of claim 33 furthercomprising latch means for transforming said light emitting means to astate of generally steady radiation after the time delay intervalterminates.
 35. The security system of claim 33 further comprisingelectronic message means for generating a voice message for transmittalfrom said housing means, said electronic message means being responsiveto said switch means.
 36. The security system of claim 33 wherein saidcircuit means further comprises nuisance delay means for preventingdeactivation of said electromagnetic means in the event said switchmeans is not actuated for a time which exceeds a pre-establishednuisance delay period.
 37. The security system of claim 33 furthercomprising alarm means responsible to said first signal for generatingan audible alarm at said housing means.
 38. The security system of claim37 wherein said oscillation means further pulses said alarm means toproduce an oscillatory audible alarm during the time delay interval andsaid audible alarm transforms to a steady state after termination of thedelay interval. .Iadd.39. A door security system comprising:housingmeans mounting electromagnet means activatable for generating a magneticfield; armature means adapted for mounting to a door and attractable bysaid electromagnet means for magnetic bonding therewith; sensor meansfor generating a signal; electronic message means for generating a voicemessage for transmittal from said housing means, said electronic messagemeans being responsive to said signal means; and delay means responsiveto said signal for deactivating said electromagnetic means after apre-established delay interval. .Iaddend. .Iadd.40. The security systemof claim 39 wherein said sensor means further comprises motion sensingmeans. .Iaddend. .Iadd.41. The security system of claim 39 wherein saidsensor means further comprises presence sensing means. .Iaddend..Iadd.42. The security system of claim 39 wherein said sensor meansfurther comprises switch means. .Iaddend. .Iadd.43. The security systemof claim 39 wherein said electronic message means produces informationrelating to the delay interval. .Iaddend. .Iadd.44. The security systemof claim 39 and further comprising light emitting means mounted at saidhousing means for emitting a visible light during said delay interval..Iaddend. .Iadd.45. The security system of claim 39 wherein said voicemessage is transmitted during said delay interval. .Iaddend. .Iadd.46. Adoor security system comprising:housing means mounting electromagnetmeans activatable for generating a magnetic field; armature meansadapted for mounting to a door and attractable by said electromagnetmeans for magnetic bonding therewith; circuit means disposed in saidhousing means comprising input means for receiving an input signal, saidcircuit means comprising electronic message means for generating a voicemessage for transmittal from said housing means, said electronic meansbeing responsive to said input signal; and release means responsive tosaid input signal for deactivating said electromagnetic means after apre-established delay interval. .Iaddend. .Iadd.47. The security systemof claim 46 further comprising sensor means for sensing motion andwherein said input signal is generated by said motion sensor means..Iaddend. .Iadd.48. The security system of claim 46 and furthercomprising presence sensor means, and wherein said input signal isgenerated by said presence sensor means. .Iaddend. .Iadd.49. Thesecurity system of claim 46 and further comprising a panic bar and aswitch actuatable by said bar, and wherein said input signal isresponsive to said switch. .Iaddend. .Iadd.50. The security system ofclaim 46 wherein said electronic message means produces informationrelating to the delay interval. .Iaddend. .Iadd.51. The security systemof claim 46 and further comprising light emitting means mounted at saidhousing means for emitting a visible light during said delay interval..Iaddend. .Iadd.52. The security system of claim 46 wherein said voicemessage is transmitted during said delay interval. .Iaddend.